In today's polluting world and outdoor lifestyle most consumers want to protect their skin, hair and scalp from harmful ultraviolet rays emitted by sun. That makes skin protection sector very important for consumer goods companies.
Consumers from different parts of the world have different characteristics of their skin. This is attributed to their genetic structure and geographical conditions. But invariably almost all consumers from different part of the world want to protect their skin, hair and scalp from harmful UV rays while exposing themselves to sunlight.
There are several ways by which consumers may obtain photoprotection of skin from sunlight especially from UV radiation. Sunscreens/sunblocks are generally used for this purpose. Sunscreens are generally organic molecules that absorb the UV radiation and emit the energy in a different form, for instance in the visible range of the spectrum or in the form of heat, thereby protecting the skin against irritation and sunburn. Sunscreens are generally small organic molecules.
Similarly sunblocks help to protect the skin against possible irritation and sunburn. These sunblocks generally comprise inorganic particulates (like ZnO, TiO2) that reflect the incident UV-visible rays thus protecting the skin.
Formulations using these molecules in the form of a cream, a lotion, gel, or spray are widely known in the industry.
People have also tried to use other natural substances (like green tea extract or other herbs extracts) alone or along with a chemical sunscreen for effective photoprotection of skin.
One of these chemical sunscreen is a derivative of dibenzoylmethane which is known as 4-t-butyl-4′-methoxydibenzoylmethane sold as Parsol 1789™ (or Avobenzone™), is a well known UVA sunscreen used in personal care composition. The problem associated with this sunscreen is its relatively unstable nature. Efforts have been made to add some external molecule, like Octocrylene™, to improve stability of Parsol 1789 in formulations. Investigations are ongoing throughout the world to find other alternatives to improve stability and the photoprotection efficiency of Parsol 1789™.
So there is a need to develop a personal care composition with improved stability of dibenzoylmethane derivative or Parsol 1789™.
U.S. Pat. No. 5,306,486 (McCook et al., 1994) describes a cosmetic composition including green tea and a sunscreen compound which is effective to at least partially block ultraviolet radiation from harming human skin.
US 2006/0275241 (Padlo et al., 2006) describes a cosmetic towelette product which includes a water-insoluble substrate and cosmetic composition in contact with the substrate. The composition includes a copolymer structured from in part a vinyl ester of a C3-C20 acid and a tea extract delivered in a cosmetically acceptable carrier. The combinations of copolymer and tea extract ensure that color changes in the product are minimized.
EP 1 640 041 (Henkel, 2006) discloses cosmetic skin treatment agents, primarily providing anti-ageing benefits, in the form of an oil-in-water emulsion, the emulsion containing taurine and at least one linear primary fatty or wax alcohol having an alkyl chain length of 20-40 carbon atoms. Examples are disclosed in this patent publication where dibenzoylmethane sunscreens and Kombucha are present in skin care compositions. Kombucha is a fermented tea beverage produced by fermenting sugared black tea with tea fungus (Food Chemistry, 102 (2007) 392-398). Kombucha is generally available from Sederma under the brandname Kombuchka™. Kombucha or Kombuchka™ is usually added in skin care composition at about 1 to 3% w/w. Being a black tea extract based product, Kombucha typically comprises from about 1% to a maximum of 2.8% theaflavin. Thus such skin care compositions comprising Kombucha generally comprise 0.01 to a maximum of 0.09% w/w theaflavin. The present inventors have determined that the benefits of the present invention cannot be obtained by inclusion of such low amounts of theaflavin
Surprisingly, the present inventors have found that theaflavin or black tea extract having higher levels of theaflavin, can act as a photostabilizer for dibenzoylmethane derivatives or Parsol-1789™. Aqueous extract of black tea typically contains a minimum of 0.1 to a maximum of about 2.8% w/w theaflavin and in rare cases up to 3% w/w theaflavin. Most black tea extracts contain theaflavin from 1 to 2% w/w (Vermeer et al., J. Agric. Food Chem, 56, 12031-36 (2008)).